Flaviviruses are arthropod-transmitted viruses and contribute to staggering numbers of human infections and significant deaths occurring annually across the globe. Members of this virus family are listed as NIAID Category A, B and C priority pathogens. In order to explore cellular antiviral factors towards flaviviruses, we screened, using an innovative iterative approach, a library expressing genes from cells treated with interferon-1 and identified DNAJC14 as able to mediate protection from yellow fever virus (YFV)-induced cell death. Expression of both hamster and human DNAJC14 results in inhibition of YFV replication. In this project, we will 1) address the breadth of DNAJC14 as an anti- flaviviral protein, 2) investigate the features of DNAJC14 and YFV required for inhibition, 3) investigate the mechanism of DNAJC14-mediated inhibition of YFV, and 4) study whether altered DNAJC14 levels can affect YFV pathogenesis in a small animal model. Understanding how this host factor mediates inhibition may lead to strategies to prevent infection and/or disease caused by human pathogenic viruses in the Flaviviridae family. PUBLIC HEALTH RELEVANCE: Project Narrative Flaviviruses are arthropod-transmitted viruses contributing to staggering numbers of human infections and significant deaths worldwide. We identified a host protein, DNAJC14, as inhibitory to cell death caused by the flavivirus, yellow fever virus and will investigate the spectrum and mechanism of action of DNAJC14 as an anti- flavivirus protein. Understanding how this factor influences the outcome of flaviviral infection may lead to strategies to prevent infection and/or disease caused viruses in the Flaviviridae family.